This invention relates to a roof support pin in general and in particular to a roof support pin of the type employing a compressible tube for engagement with a roof bore. The prior art teaches the use of a compressible tube for roof support. In the prior art, a tube is forced into an undersized bore where it frictionally engages the bore to anchor itself. The prior art teaches the use of the bore to compress the tube.
In coal mines, it is generally necessary to leave a roof layer of top coal or shale through which a roof support pin must be mounted. This roof layer of top coal is quite fragile, and the force exerted on it by a tube being inserted into a undersized bore could result in the fracturing of the top coal thereby causing it to either fall or create a very dangerous condition. It is therefore important that the bore opening not be used to compress a tube.